Interval measuring system



Oct. lll, 1,949. E. J. lsBlsTER INTERVAL MEASURING SYSTEM 5 Sheets-Sheetl Filed April 24, 1945 ATTORN EY Oct. l1, 1949. E. J. lsBlsTER INTERVALMESURING` SYSTEM Filed April 24, 1945 3 Sheets-Sheet 2 INVENTOR EQ/C d./SB/STER TTORNEY Patented Oct. 11, 1949 The Sperry Corporation Ware acorporation of'D'ela- Application .epi-i1 24,1945, serial No. 590,088f1i claims. (o1. irs- 44) The present invention relates generally tointerval measuring systems, and more particularly to-systems foraccurately measuring the time intervalbetween similar points on twooutput pulses and employs revolution counting` apparatus responsive totwo independent driving members. It is ofttimes desirable to measure thetime interval betweensuccessive voltage or current wave pulses with.great accuracy. This is true, for example, in Loran navigationapparatus, and, therefore, it 1s an object of thepresent invention toprovide a novel interval measuring system having output circuitsproducing. pulses, the time interval between the pulse of one circuitand that of4 another circuit being determined withA extreme accuracythrough the use of suitable phase-shifting apparatus, said time intervalbeing. indicated by means of a revolution counter.

Revolution counters have long been known consisting of a train ofintermittent gears actuated f by a single driving member and havingseveral numbering elements, such as drums, each provided with a seriesof numerals. The numbering elements are coupled together in a certaintransmission ratio to select for. exhibition one numeral from those on,each drum, and the selected nul merals constitute a ligure which isproportional to the number of revolutions performed by the. drivingmember. The gure thus assembled may be easily read without any skill orinterpolation.

These counters have. been incorporated in apparatus for indicating theposition of a drivenmember actuated. gradually by a driving member, forexample, through speed reduction gearing.

The counter is made responsive to the. drivingk member rather than. tothe driven member in order to improvey the accuracy of the positionalindication by a factor equal to the speed ratio of the driving anddriven members. It is often desirable, however, to position abruptly orslew the driven member independently of the driving, member while stillpermitting the counter' to register correctly the resultant position ofthe driven member.

The need for coarse and ne control over the driven member in order toposition the same rapidly and yet accurately is particularly acute incertain known. electronic timing apparatus of the general type employinga low frequency phase shifter and a 'high frequency phaseshifter geared'together in accordance. withY the frequencies. of the waves transmittedthereby. The waves are synchronized with a periodic reference signalandthe phase shifted low frequency waves are utilized for` selectingArecurrent portionsA of' the phase shiited highfrequency wavesto obtain aperiodic signal. delayedaprecise and unambiguous interval.. with respectto the reference signal'.

Apparatus of this character is employed. in radio navigation systemsWhere it is essential to change the reading. ot the device from oneprecise time delay between the output pulses of the system to. an othertime delay between. the output pulses of the system that may be greatlyseparated from the first indication. but requires equally preoiseadjustment. If no slewing mechanism is available, severalinvaluableminutes may be lost in making thisA 11e-adjustment solely through a necontrol. Another object of the invention is to. provide intervalmeasuring. systems or timing. apparatus employing. a plurality of phaseShifters connected together in accordance with diierent frequencies ofwaves transmitted thereby, the waves being synchronized. with a periodicreference signal, the phase-shifted waves of one frequency beingutilized for selectingv recurrent portions of the phase-shifted waves ofanother frequency tovobtain aperiodic signal delayed` a preoise andunambiguousfinterval with respect to the f reference signal.

Another object of the present invention to provide means for abruptlypositioning or slewing a driven member independently of a normal drivingmemberwhile permitting a counter mechanism to maintain syn-chronism withthe driven member and: to register a gure representative of itsresultant position.

Generally speaking,v the invention contemplates providing-connectivemeans for actuating a driven member, such as the shaft of a phaseshifter, by two independent driving. members, which are re-` ferred tothroughout the specification as a fine or precise control and a coarseor slewing control. The connective means takes the form of aclutchingmechanism or differential gear unit. A counter of the typedescribed above is made responsive to the iine controlfor composing afigure repre sentative of the position of the driven member. Anotherconnective means is included in the coupling between two` adjacentnumbering elements of the counter, for example, between the hundreds andthousands drums. This latter connective means not only permits' thenumbering element representing the lower decimal place to driveintermittently the element representing the next higherA decimal placebut also allows the coarse control. to change the numeral selected forexhibition by the greater-valued numbering element, e. g. the thousandsdrum, in accordance with an equivalent change effected by the coarsecontrol in the position of the driven member.

The invention will be more fully understood by reference to the specicembodiments illustrated in the drawings and the following descriptionthereof.

In the drawings,

Fig. 1 is a schematic block diagram of timing apparatus employing acounter type of time delay indicator and arranged in accordance with theinvention to permit slewing or abrupt changes in the timed interval;

Fig. 2 is a cross-sectional view taken along broken line 2-2 of a detailof the counter shown in Fig. 1; and

Fig. 3 is a schematic block diagram of an alternative form of slewingmechanism.

Fig. 4 is a diagrammatic view illustrating the wave relationships ofcomponent parts of the system.

Similar reference numerals are employed to indicate corresponding partsin the above figures.

Referring now to Fig. 1, the invention is illustrated in combinationwith known timing apparatus wherein a source II of stable frequencyprovides sinusoidal waves -which are utilized as the basis for preciseinterval measurements in the manner now to be described. The waves fromsource II are supplied to a frequency divider I2 which is adapted toreduce the frequency of the applied waves by a factor M and to providesinusoidal signals at a subharmonic of the frequency generated by sourceII to a further frequency divider I3. Divider I3 is generally similar todevice I2, and is designed to lower the frequency of the incoming wavesby a factor N. The output Waves from divider I3 are supplied to a squarewave generator I4 Whose function consists of forming substantiallyrectangular Waves accurately synchronized at one half the frequency ofthe applied signals.

The output of generator I4 is connected to a reference pulse selectorI5. The selector I5 comprises a trigger circuit such as a multivibratorwhich is adapted to alter its quiescent condition or be turned on" bythe leading edge of the W frequency wave from generator I4. The selectorI5 is returned to its initial quiescent condition or turned off by thenext cycle of the waves issuing from source II subsequent to the wavefrom generator I4. This is accomplished by the provision of a pulsegenerator IB which has its input supplied from source II and its outputapplied to the reference pulse selector I5. A pedestal Wave whosecommencement and conclusion are determined b-y circuits I4 and I6,respectively, appears on output lead 52 of selector I5. The recurrencerate of this pedestal Wave is 10W and yet its rear edge is preciselydened; consequently, it is well adapted to serve as a low frequency timereference signal.

The pulse generator IE may comprise distorting amplifiers which clip thetops of the Waves from source I i and form square waves which may thenbe differentiated to produce pulses suitable for triggering selector I5.Pulse generator I6, on the other hand, may comprise the well-knownsatrurable transformer type of pulse forming circuit.

A pulse whose trailing edge is delayed a precise interval with respectto the termination of the time reference signal on lead 52 is obtainedin the following manner: Fine, medium, and coarse continuouslyadjustable linear phase Shifters I1, I8 and I9, respectively, aresupplied with sinusoidal Waves of harmonically related frequencies overleads 2I, 22 and 23, respectively, from source II, divider I2 anddivider I3, respectively, These phase Shifters are geared together inaccordance with the frequencies of the Waves transmitted thereby. A finecontrol knob 24 is attached to a hollow shaft 25 on which are fixedgears 25, 21 and 28. Gear 28 meshes with a gear 29 mounted on a shaft 3Iadapted to actuate phase shifter I'I. Gear 2l is coupled through speedreduction gearing 32, 33 and 34 te drive a shaft 35 associated withmedium phase shifter I8. A gear 35 is xed to shaft 35 and meshes withgear 3l connected to a shaft 3B. Shaft 38 forms one input to adifferential gear unit 33 whose output shaft 4I serves to control thecoarse phase shifter I9.

It is seen that phase `shifters I'I, I8 and I9 are interconnected bygearing in such manner that rotation of the knob 24 -producesprogressively reduced rotation of the fine, medium and coarse phaseshifters with the result that the harmonically related series of wavessupplied over leads 2|, 22 and 23 are subjected to substantially thesame time delay, although the phase shift of the highest frequency wavesis generally many times 360, while the shift of the lowest frequencywaves is a fraction of a period.

The phase shifted outputs of devices I'I, I8 and I9 are applied tosimilar pulse generators 42, 43 and 44, respectively, corresponding topulse generator Iii. Pulse generators 42, 43 and 44 supply triggeringsignals to nal, second, and first selectors 45, 46 and 41, respectively.These selector circuits may be generally similar to reference pulseselector I5. First selector 41 is adapted to be turned on .by thetrailing edge of the square wave supplied by generator I4 over a lead 48and turned off by the next signal from pulse generator 44. The pulse orpedestal wave formed by the operation of the first selector 4l is fed bya lead 49 to the second selector 45 Where its trailing edge triggers onthis latter circuit. The first ensuing pulse from generator 43 returnsselector 46 to its normal quiescent condition, and determines the endingof the pedestal Wave formed by the second selector. This pedestal waveis supplied through a lead 5I to the final selector 45 where itscessation initiates another pedestal terminated by the next succeedingpulse issuing from generator 42.

The end of the pedestal generated by final selector 45 and appearing onoutput lead 53 is thus delayed a precise and unambiguous time intervalwith respect to the corresponding portion of the pedestal created Ibyreference pulse selector I5 and appearing on output lead 52. Thisinterval is proportional to the total number of degrees through whichshaft .3| of the fine phase shifter Il has been rotated. The function ofthe coarse and medium phase Shifters is to eliminate any ambiguity inthe measurement of the time delay by keeping track of the integralnumber of revolutions through which shaft 3i has been rotated. Theaccuracy with which the time delay may be determined is substantiallyindependent of the accuracies of the medium and coarse phase Shifters.The pulses produced by generator 44 must, however, occur in an intervalpreceding the trigger pulse from generator 43 not greater than theperiod of the medium frequency Waves, and the trigger pulse fromgenerator 43 in like manner must immediately precede the pulse that itis desired to select from generator 42 by an interval not greater thanthe period of the waves from source II.

One use of this invention is to measure the time sesam output leads 52and '53, since the outputs of these.

leads have a very accurate time difference.

'The time interval vselect-ed by the. above apparatus is convenientlyindicated by a. .revolution counter '54 driven in synchronism with the.phase Shifters by means of bevel gear 55 `attached to: counter inputshaft 56 and meshed with -gear 26. The 'counter 54 is generally ofconventional design having a units, tens, hundreds, 'and thousands drum55|, 58, 59, and 62|, respectively, 'connected' together throughlintermittent gearing so that`r a complete turn of one ydrum or counterwheel will?v cause la small angular displacement of the adjacent' drumon `the left. The interconnectionY between the units and tens counterwheels 51 andl 58 and between the tens and hundreds counter wheels 581and S includes star wheels 62 and 63', respectively. Star wheels 62 vand63 operate in ia conventional manner to couple mutilated gears attachedto counter 'wheels on the right with fulltoo'thed ygears xed to counterwheels on the left.

The star wheel lbetween the hundreds and thousands drum, however, is notconventional but is separated into two independent portionsA 65 and 66.The left-hand portion (ity is a pinion nieshed with the gear attached todrum 6|, while the right-hand .portion 65 is a istar wheel generallysimilar to wheels 62 and E3 but narrower by approximately the width ofpinion 66. Star wheel 65 and pinion (it are connected through the agencyof a differential B1. Idler gear 68 couples wheel 65 with .one input ofdifferential El Whose output gear 69 is adapted to drive pinion 66through idler gears 1| and 12 mounted for joint rotation on a sleeve 13.

Fig. 2 illustrates a cross section of the intermittent gearing includedinthe coupling between counter wheels 59 and tl. The star wheel 65 hasits alternate teeth extending entirely across and half way across itswidth soy that the left-hand portion of the wheel has a full number`of'teeth and the right-hand -portion half the full number of teeth. Therightnhand half of Wheel B5 en? gagesa mutilated gear if! and theleft-hand half engages a mutilated gear '15. The mutilated gear Mcomprises a cylindrical surface which is provided with a recess or notch16 whose' sides coinlci-de with two teeth of the mutilated gear T5, thevremainder ofthe latter gear being cut away to its root circle. Two ofthe teeth on the right-hand portion of the star wheel 65 normally restupon the surface ofthe mutilated gear 14, and prevent the wheel 65 fromlbeing turned inadvertently; The relation lbetween the recess 16 and thetwo teeth of the mutilated gear T5 is such that when counter wheel 59makes a complete revolution, one of the teeth resting against gear 14will beallowed to extend: into the notch. 15 and' permit an angularadvance of the star wheel 65. The speed ratio between counter wheels 59and 5| is `such as to effect va tenth of a revolution in the latter forone complete revolution of' the former.

The apparatus described in the foregoing with the exception of thedifferential gear units 39r and 67 `and the split star wheel 65. 66 doesnot of itself part of the. invention, for, although not as yetwell-known, apparatus of this general character Vhas .been developed.prior to the slewing apparatus evolved by the present inventor.

.It has. been found necessary in .practical applii-V cation-s of timingapparatus to change from i. one time 4delay* to a ,greatly differentvalue in a.

matter of seconds.. It is. evident that this would be impossible 'bymanipulating. only the ne. control knob 24. A coarse control knob 11 istherefore. provided fixed to a shaft 18 ,positioned for convenienceconcentrically with hollow shaft,v 25 and extending therethrough tofacilitate; transfer of manipulation from. fine knob 24 to coarsefkniob. 'V11' and. vice versa.. Shaft 18 is connested through bevelgears 19 to a second. input shaft 8| .of the differential gear unit 61,and is also coupled throughbevel gears 82, shaft'83 and beveK gears 84=to a second input of the-differential gear unit 39.

The coupling of the slewing lknob 'H to the ydifeferential. gear units39 vand 51 permits the intro-v.

duction of large changes in the time delayed signal by actuating thecoarse phase shifter i9 independently of thexother phase Shifters andconcurrently `registering the large time delay change on the counterWheel 6|? independently of the.v time delay indicated in accordance withthe position. of the fine control knob 2'4. A detent cam. 8-5 fixed toslewing shaft 18 cooperates with 'a spring loaded roller 85 to insurethat the delay? introduced .is equal to an integral multiple of themaximum unambiguous :delay obtainable from. the medium phase shifter I8.The detent -8 5' also.A predetermines the alignment of the numeral,selected by drum 6| corresponding to the inserted time delay.

In the mechanical operation of the structure shown` in Fig.. 1, rotationof the ne knob 2li actu. ates the counter '54 in synchronism with thephase. Shifters H', I8 'and t9; The drum 59, in the act of completing'one revolution, drives the drum 61|l through. the differential 51 whoseshaft 8| locked .by the 'detent 85. Since input shaft 83 ofdifferentialv 39l i's also locked by the 'same detent, shafts 33I `and41' 'controlling the coarse phase shifter I9 are in effect connectedtogether. It i's'to beY noted that each time any' counting wheel orwheels Aare rotated they move at the speed of the units wheel 51 eventhough the d'erenti'al may :be included in the coupling between Wheels.

When the coarse control knob T1 is rotated, the detent 8.5 isoverpowered, and shafts 8| and 83- are `alatuptly actuated in unison anydesired numlber of steps or' jumps. Input shaft 38 of differential 39vis eiectively locked by the large Speed multiplica-tion afforded by thegearing between it and the line control knob 2.4, while the star wheel655- locks the ralternate input to the differential gear unit. 551.Thus, counter wheel `6| and the coarse phase shifter i9 are rotated insynchronism and the detent insures that 'their rest-ing position ispredetermined.

For a 'specic' 'example and. for illustrative pur, poses only, thefrequency of source l i may be. 20 kc. and the dividing factors M and Nassociated with the frequency dividers l2? and I3, respectively, Inaybe20` and 5, respectively, with the result. that the. frequency of theWaves passing thneugh. medium phase shifter |8 and coarse phase, shifter|'9 will be 1000 cycles and 200 cycles', respectively. Tlrie speed;ratio between ne control knobftand shafts 3|, 35 and A toa-gres withlthese 'conditions will: be 1:1, 20:1 and 100:1, 'respectively. Thedetent 85 will necessarily provide ve spaced steps in order. thatA thechange of delay introduced by the slewing control 11 be equal to someintegral multiple period of the waves transmitted by the medium phaseshifter I8. This assures that the slewing operation takes place in exact1000 microsecond steps so that electrical synchronism of the system ismaintained. The total delay time which may be unambiguously measured is5000 microseconds, since this is the period of the 200 cycle wavesassumed to be transmitted by the .coarse phase shifter |9.

' The thousands drum 6| will, therefore, be marked from to 4 overone-half the circumference and repeated over the other half of the drum,while the other drums will be marked from 0` to 9 evenly spaced aroundtheir peripheries. Since a complete revolution of the phase shifter |1when transmitting 20 kc. corresponds to 50 microseconds, the gears 26and 55 will be so proportioned that 1/5 of a revolution of shaft 3| or,what amounts to the same thing under the specified relations-hips, 1/5of a revolution of knob 24l effects a full revolution of the units drum51. Thus, it is seen that indicator 54 will indicate directly in decimalparts of a second.

yThe slewing mechanism disclosed in Fig. 1 makes possible twomeasurements separated by the maximum delay after rotating the coarsecontrol knob 11 no more than 3/5 of a turn and the fine control knob 24no more than 10 revolutions. It is evident that the ability to roughlyset the delay greatly facilitates the emplOyment of the system.

Referring now to Fig. 3, there is illustrated a positive clutchmechanism which may be employed in place of the differential gear unit61 shown in Fig. 1 associated with the counter 54. An idler gear 9|having a jaw clutch 92 formed integral therewith is freely rotatable Iona shaft 93 .but restrained from axial movement therealong by collars 94and 95 pinned to the shaft 93. Gear 9| normally meshes with star wheel65 vand pinion 66 associated with counter wheels 59 and 6|,respectively, discussed with reference to Fig. 1.

In ordinary operation, the -counter 54 may be actuated by the nnecontrol kndb 24 in synchronism with the phase Shifters I1, I8 and I9 andthe hundreds drum 59 is free to drive the thousands drum 6| through theagencies of gears 65, 9| and 66. A shaft 96 connected to thedifferential 39 through bevel gears 91, shaft 98, bevel gears 99, shaft|0|, and gears 64 is aligned with shaft 93 and is formed with a sleeveportion |02 adapted to receive an end of shaft 93. A pin |03 fixed toshaft 93 cooperates with a groove |04 to permit sliding movement ofshaft 93 with respect to shaft 96, while coupling their rotationalmotions. A compressional spring |05 placed within the sleeve |92 tendsto force shafts 93 and 96 apart. The sleeve |02 is tenminated by a jawclutch |06 adapted to engage clutch 92 when the shaft 93 is forcedtowards the shaft 96 .by pushing in coarse control knob 11 mounted onshaft 93. A. splined portion |01 cooperates with a splined bushing |96to prevent rotation of shaft 93 except when clutch portions 92 and |06are fully engaged and when gear 9| is slid out of engagement with starwheel 65. The detent carri 85 is fastened to the shaft 96 and permits itto rest only at equiangularly displaced positions. The numbers of theclutch gearing teeth, the splines and the detent steps are related by acommon multiple, for example, 5.

The normal operation ofthe structure of Fig.

3 is substantially the same as that of Fig. 1. If,v

however, it is desired to alter the time delay in thousand microsecondsteps, coarse control knob 'Il is pushed in against the pressure ofspring |05 sliding gear 9| out of mesh with star wheel 65. When theclutch portions 92 and |06 are fully engaged and gear 9| couples onlypinion 66, spline |01 is freed from locking engagement with bushing |08.Knob 11 may now be rotated the desirednumber of detent steps. Thethousands wheel 6| and the coarse phase *shifter I9 are forced to turnin unison. A shoulder |09 on collar 94 locks the star wheel 65 andprevents any manipulation of the fine control knob 24 from disturbingthe relationship between the counter indication and the angular positionof the coarse phase shifter I9. The detent 95 not only insures that theelectrical portion of the system is always maintained in synchronism,but also predetermines the meshing of gear 9| with star wheel 65 andspline |01 with bus-hing |08 when upon releasing knob 11, spring |05returns the gear 9| to its normal free running position coupling thehundreds drum 59 te the thousands drum 6|. It is to be observed that thedetent need not be strong since shaft 9.3 is locked by means of thespline |01 when the ne control knob 24 is in use.

The structure of Fig. 3 is preferable to that of Fig. 1 under certainconditions, since only one gear, gear 9|, loads the counter andtherefore more liberal mechanical tolerances are permissible without therisk that backlash will confuse the reading of the thousands drum 6|.

Fig. 4 is a diagrammatic view showing the Wave relationships of theoutputs of the various components of the system, each component referredto in this case being designated by the numeral omitting the primeoccurring in Fig. 4. For example, the wave form designated 1| in Fig. 4indicates the frequency output of source Following out the examplepreviously -given herein, twenty cycles of this frequency corresponds intime to one cycle of the output of the frequency divider I2, whoseoutput is designated I2' in the drawing of Fig. 4. On the other hand,the output of the frequency divider I3 is a wave whose cycle correspondsto ve cycles of that of the output of frequency divider I2. I4designates the square wave output of square wave generator I4, and |5designates the pulse output of the output lead circuit 52. The coarsephase shifter I9 has an output frequency the same as that of I3',ibut-this frequency is shifted in phase in ac cordance with theadjustment of the knob 24. The output of selector 41, designated 41 inFig. 4, is accordingly shifted as to duration of the square wave, asindicated by the arrow in Fig. 4; i. e., if the wave output of coarseyphase shifter I9 shifts, the duration of the square wave of theselector 41 will correspondingly vary. Similarly, the output of thepulse generator 43, fed from the medium phase shifter I8, is designated43 in the drawing and this output voltage, which corresponds to afrequency of 1000 cycles, is shifted in phase with adjustment of themedium phase shifter I8, and this shift in phase automatically causesthe output of the second selector 46, designated 4G in Fig. 4, to shiftback and forth, as indicated by the arrows, as a whole, so that theoutput of final selector 55 similarly shifts. Thus, through use of theseveral phase Shifters and manner of tying these phase Shifters togetherto avoid ambiguity, an extremely accurate timing of the interval betweenthe output pulse 45 and that of I5' is obtained.

Since many changes cou-ld be lmade in the above construction and manyapparently widely different embodiments of this invention could be madeWithout departing from the scope thereof, .it is intended that allmatter contained in the 4above description orV shown .in theaccompanying drawings shall -be interpreted as illustrative and not in alimiting sense.

What is claimed is:

1., In electronic timing apparatus employing a low frequency phaseshifter and. a high frequency `phase shifter geared together inaccordance with the frequencies f the. waves transmitted thereby, .thewaves being synchronized with a periodic reference signal, and the phaseshifted low frequency waves being utilized for vselecting recurrentportions of the phase shifted high frequency Waves to vobtain a periodicsignal delayed a precise and unambiguous interval With respect to .saidreference signal, the combination comprising a revolution counterresponsive to said high frequency phase shifter for indicating the timedelay, means for introducing a large change in said time delay byactuating said loW frequency phase shifter independently of said highfrequency phase shifter, and means for registering said large time delaychange on said counter independently of the time delay indicated inresponse to said high frequency phase shifter.

2. In electronc timing apparatus employing a low frequency phase shifterand a high frequency phase shifter geared together in accordance withthe frequencies of the Waves transmitted thereby, the Waves beingsynchronized with a periodic ref-erence signal, and the phase shifted.low frequency waves .being utilized for selecting recurrent portions ofthe phase shifted highfrequency Waves to obtain a periodic. signaldelayed a precise and unambiguous interval with respect to saidreference signal, the lcombination comprising a revolution counterresponsive to said high frequency phase shifter for indicating the timedelay, a first differential mechanism for introducing a large change. insaid time delay by actuating said loW frequency phase shifterindependently of said high frequency phase shifter, and a seconddifferential mechanism for registering said large time delay change onsaid counter independently of the time delay indicated in response tosaid high frequency phase shifter.

3. In electronic vtiming apparatus employinga low frequency phaseshifter and a high frequency' phase shifterl geared. together inaccordance with the frequencies of the waves transmitted thereby, theWaves being synchronized with a periodic reference signal, and the phaseshifted loW frequency waves being utilized for selecting recurrentportions of the phase shifted high frequency waves to obtain a periodicsignal delay a precise and unambiguous interval with respect to saidreferance signal, the combination comprising a revolution counterresponsive to said high frequency phase shifter for indicating the timedelay, a differential mechanism for introducing a large change in saidtime delay by actuating said low frequency phase shifter independentlyof said high frequency phase shifter, and a positive clutch mechanismfor registering said large time delay change on said counterindependently of the time delay indicated in response to said highfrequency phase shifter.

4. In electronic. timing apparatus-employing .a 10W frequency phaseshifter and a high frequency phase shifter geared together inaccordancewith the frequencies of the ywaves transmitted thereby,

einem the Waves being synchronized with a periodic reference signal, andthe phase shifted low frequency Waves being utilized for selectingrecurrent portions of the phase ,shifted high frequency waves to obtaina periodic signal delayed a precise and unambiguous interval withrespect to said reference signal, the Vcombination comprising a counter,driven. .in..accerdance withy .the position of said highfrequency phaseshifter, said counter vincluding .a plurality of interconnectednumbering elements, leach provided With a set of numerals .and-movableto select for exhibition a single numeral. fromeach set, the selectednumerals constituting a gure representing the time delay of saidsignal,lmeansfor introducing a large change in said time .delay by actuatingsaid low frequency phase .shifter independently of said high frequencyphase shifter, and means for registering said large time delay change onsaidl counter independently of .the time delay indicated in accordancewith the position of said high frequency phase. shifter.

5. In electronic timing apparatus providing rst and second phaseShifters for receiving a rst and a second harmonically related series ofwaves, respectivelysaid Waves being synchronized with .a periodicreference signal and said phase .shifters beingcoupledin such manner asto subject said waves to substantially the same time delay `with theresult that the amount of phase shift suffered by said rst waves servesat least in part to determine the number kof integral periods by whichsaid second waves are delayed, and wherein said first waves are.employed in the selection 0f MPOITtOIlv 0f Saidsecond waves forobtaining a signal precisely .delayed with respect to said referencesignal and recurring at a submultiple of 4the frequency of-said secondWaves, the combination Vcomprising.a revolution-.counter respon'- sve.to said .second phase .shifter for indicating the. time delay of vsaidsignal, means for actuatingr said first phase shifter independently ofsaid second phase .shifter tochange the phase of said rst, waves by an.amount substantially correspondingf to a. predetermined number ofcycles of said second waves,. and means for registering a time, delayVchange .on said Vcounter corresponding exactly to said.predeterminednumber of cycles independently of the .time delay indicated in responseto,v saidv second phase shifter.

6. .In electronic .timing apparatus providing first. and second phaseshifters for receiving a first and a secondharmonically related seriesof Waves, respectively, said Waves being synchronized with a. periodicreference signal and said phase Shifters beingr coupled in such manneras to subject .said waves. tosubstantially the same time delay with Vtheresult. that the amount of phase shift suffered. by said rst,v Wavesserves at least in part .tof determine the number of integral periods bywhich said .second waves are delayed, and wherein said first Waves areVemployed in the selection of .a portion of saidr second Waves forobtaining a, signal precisely delayed with respect to said` referencesignal and with respect to said unshiftedfwaves, said .signal recurringat a submultipleof the vfrequencyofA said second Waves, the combinationcomprising a revolution counter responsive'to said second phase shifterfor indicating the time delay of :said signal, a first differentialmechanism intermediate said phase Shifters for actuating said first.phase shifter independently of saidsecond phaseshifter to change thephase of said first Waves by an amount sub- 7:5 stantially-correspondingto apredetermined nurn- Vber of cycles of said second waves, and asecond differential mechanism for registering a time delay change onSaid counter corresponding exactly to said predetermined number ofcycles indep-endently of the time delay indicated in response to saidsecond phase shifter.

7. In electronic timing apparatus providing first and second phaseShifters for receiving a nrst and a second harmonically related seriesof waves, respectively, said waves being synchronized with a periodicreference signal and said phase shifters being coupled in such manner asto subject said waves to substantially the same time delay with theresult that the amount of phase shift suffered bysaid first waves servesat least in part to determine the number of integral periods by whichsaid second waves are delayed, and wherein said first waves are employedin the selection of a portion of said second waves for obtaining asignal precisely delayed with respect to said reference signal and withrespect to said unshifted waves, said signal recurring at a submultipleof the frequency of said second waves,

`the combination comprising a revolution counter responsive to saidsecond phase shifter for indicating the time delay of said signal, adifferential mechanism intermediate said phase Shifters for actuatingsaid rst phase shifter independently of said second phase shifter tochange the phase of said first waves by an amount substantiallycorresponding to a predetermined number of cycles of said second waves,and a positive clutch mechanism for registering a time delay change onsaid counter corresponding exactly to said predetermined number of`cycles independently of the time delay indicated in response to saidsecond phase shifter.

8. In electronic timing apparatus providing rst and second'phaseshifters for receiving a rst and a second harmonically related series ofwaves, respectively, said waves being synchronized with a periodicreference signal and said phase shifters being coupled in such manner asto subject said waves to substantially the same time delay with theresult that the amount of phase shift suffered by said first wavesserves at least in part to determine the number of integral periods bywhich said second waves are delayed, and wherein said first waves areemployed in the selection of a portion of said second waves forobtaining a signal precisely delayed with respect to said referencesignal and with respect to said unshifted waves, said signal recurringat a -submultiple of the frequency of said second waves, the combinationcomprising afirst differential gear unit having two input gears and anoutput gear, said output gear and one of said input gears being includedin the coupling between said phase Shifters, a revolution counter havinga plurality of intermittently coupled scales, one of said scales beingactuated in response to said second phase shifter for indicating thetime delay of said signal, a second differential gear unit having twoinput gears and an output gear, said output gear and one of said inputgearsy being included in the coupling between two of said counterscales, a slewing member coupled to both the other of said input gearsof said differential gear units for introducing a change in the phase ofsaid first waves substantially corresponding to a predetermined numberof cycles of said second waves and registering a time delay change onsaid counter corresponding exactly to said predetermined number ofcycles.

9. In electronic timing apparatus providing first and second phaseShifters for receiving a first and a second harmonically related seriesof waves, respectively, said waves being sychronized with a periodicreference signal and said phase Shifters being coupled in such manner asto subject said waves to substantially the same time delay with theresult that the amount of phase shift suffered by said first wavesserves at least in part to determine the number of integral periods bywhich said second waves are delayed, and wherein said first waves areemployed in the selection of a portion of said second waves forobtaining a signal precisely delayed with respect to said referencesignal and with respect to said unshifted waves, said signal recurringat'a submultiple of the frequency of said second waves, the combinationcomprising a differential gear unit having two input gears and an outputgear, said output gear and one of said input gears being included in thecoupling between said phase Shifters, a slewing member coupled to theother of said input gears,'a revolution counter having a first scaleactuated in response to said second phase shifter and at least a secondscale normally locked and intermittently coupled to said nrst scale,said scales serving to indicate the time delay of said signal, meanscoordinated with said slewing member for unlocking said second scale andincapacitating the coupling to said first scale, and means positivelycoupling said first phase shifter and said second scale for changing theindication of said counter in accordance with the change effected bysaid slewing member in time delay of said signal.

l0. In electronic timing apparatus providing first and second phaseShifters for receiving a first and a second harmonically related series0f waves, respectively, said waves being synchronized with a periodicreference signal and said phase Shifters being interconnected in suchmanner as to subject said waves to substantially the same time delaywith the result that the amount of phase shift suffered by said rstwaves serves at least in part to determine the number of integralperiods by which said second waves are delayed, and wherein said firstwaves are employed in the selection of a portion of said second wavesfor obtaining a signal precisely delayed with respect to said referencesignal and with respect to said unshifted waves, said signal recurringat a submultiple of the frequency of said second waves, the combinationcomprising connective means having two input couplings for actuatingsaid first phase shifter, one of said couplings being included in theconnection between said phase Shifters, a slewing member connected tothe other of said couplings, a revolution counter having a plurality ofintermittently coupled scales, one of said scales being actuated inresponse to said second phase shifter for indicating the time delay ofsaid signal, and means coordinated with said slewing member included inthe coupling between two of said scales for registering a time delaychange on said counter corresponding to the change in the phase of saidrst waves effected by said slewing member.

1l. In electronic timing apparatus providing first and second phaseShifters for receiving a first and a second harmonically related seriesof waves, respectively, said waves being synchronized with a periodicreference signal and said phase Shifters being interconnected in such amanner as to subject said waves to substantially the same time delaywith the result that the amount of phase shift suffered by said firstwaves 13 serves at least in part to determine the number of integralperiods by which said second waves are delayed, and wherein said firstwaves are employed in the selection of a portion of said second wavesfor obtaining a signal precisely delayed with respect to said referencesignal and with respect to said unshifted waves, said signal recurringat a submultiple of the frequency of said second waves, the combinationcomprising connective means having two input couplings for actuatingsaid first phase shifter, one of said couplings being included in theconnection between said phase Shifters, a slewing member connected tothe other of said couplings, a revolution counter having a first scaleactuated in response to said second phase shifter and at least a secondscale normally locked and intermittently coupled to said nrst scale,said scales serving to indicate the time delay of said signal, meanscoordinated with said slewing member for un- ERIC J. ISBISTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,273,956 Hall Feb. 24, 19422,277,643 Holmes Mar. 24, 1942 2,387,412 Sundt Oct. 23, 1945 2,491,994Nicholson May 28, 1946 2,467,294 Shockley et al. Sept. 10, 1946Certificate of Correction Patent No. 2,484,034 October 11, 1949 ERIC J.ISBISTER It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 14, line 6, for the Word machine read member;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the ease n the PatentOfee.

Signed and sealed this 23rd day of May, A. D. 1950.

THOMAS F. MURPHY,

Assistant ommz'sszmwr of Patents.

Certificate of Correction Patent No. 2,484,084 October 11, 1949 ERIC J.ISBISTER It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfoHoWs:

Column 14, line 6, for the Word maehine" read member;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the oase in thePatent Office.

Signed and sealed this 23rd day of May, A. D. 1950.

[SML] THOMAS F. MURPHY,

Assistant Commissioner of Patents.

